Hezbollah's leader, Sheikh Hassan Nasrallah, said on Saturday that his group would abide by the resolution, which has also been endorsed by the Lebanese government.

But he added: "As long as there is Israeli military movement, Israeli field aggression and Israeli soldiers occupying our land... it is our natural right to confront them, fight them and defend our land, our homes, and ourselves."

An Israeli foreign ministry spokesman told BBC Radio Five Live that Israeli forces would respond if attacked by Hezbollah.

"If Hezbollah decides to violate the resolution and declare their own terms... well the Israeli army will certainly not stand aside and fail to respond, that's for sure," Ylgal Palmor said.

Some Israeli estimates put the number of Israeli troops now in southern Lebanon at 30,000.

On Saturday, Israeli troops reached the key target of the Litani River, while its jets hit a string of targets in Lebanon, killing some 40 Hezbollah fighters.

The Israeli army suffered its highest number of casualties in a single day since the conflict began, with 19 troops confirmed killed and a further five presumed dead after their helicopter was shot down.

One of the five was a woman, Sgt Maj Keren Tendler. Her death, if confirmed, would make her the first female soldier killed in action in the conflict.

More than 1,000 Lebanese and more than 120 Israelis have been killed in the conflict since Hezbollah militants captured two Israeli soldiers on 12 July in a cross-border raid.